The present invention relates to a method for fabricating a semiconductor device, more specifically a method for fabricating a semiconductor device, which can form a micronized gate electrode.
Recently, with the higher speed and higher integration of super-LSIs (Large Scale Integrated Circuits), the gate length is required to be shorter, and the parasitic capacitance is required to be smaller. To meet such requirements, the exposure light used in the photolithography is short-wavelength light, such as ArF excimer laser beams. In accordance therewith, photoresist materials for the micronized pattern exposure by the short-wavelength exposure light are developed.
However, the photoresist material used in the photolithography using the ArF excimer laser as the exposure light source has a disadvantage of poor resistance to plasma etching. Accordingly, when micronized gate electrodes are patterned, hard masks of oxide film, nitride film, etc. are used together with resists for the micronized pattern exposure (refer to, e.g., Wei W. Lee et al., “FABRICATION OF 0.06 μm POLY-Si GATE USING DUV LITHOGRAPHY WITH A DESIGNED SixOyHz FILM AS AN ARC AND HARDMASK” IEEE 1997 Symposium on VLSI Technology Digest of Technical Papers, p.131).
However, the above-described conventional method for fabricating a semiconductor device which patterns gate electrodes, using a hard mask has disadvantages such that when micronized gate electrodes of, e.g., a ˜50 nm line width are etched, the etching rate is varied. The above-described conventional method for fabricating a semiconductor device has found it difficult to form micronized gate electrodes with good yields.